Antifouling coating composition comprising a fluorinated resin

ABSTRACT

A process for inhibiting the fouling of a substrate in a marine fouling environment, which comprises forming on the substrate, before exposure to the said environment, a coating comprising a curable fluorinated resin of the general formula: W-L-YFC—O—R f —CFY-L-W wherein: W is a group of the general formula —Si(R 1 ) α (OR 2 ) 3-α , wherein α=0, 1, or 2, preferably α=0, R 1  and R 2  independently have the meaning of linear of branched C 1 -C 6  alkyl groups, optionally containing one or more ether groups, or C 7 -C 12  aryl or alkyl groups, and preferably R 1  and R 2  are C1-C4 alkyl groups; L is an organic linking group; Y is F or CF 3 ; and R f  is a group having an average molecular weight by number between 350 and 8000, preferably between 500 and 3000, and comprising repeating units having at least one of the following structures randomly distributed along the chain: —CFXO—, CF 2 CF 2 O—, CF 2 CF 2 CF 2 O—, CF 2 CF 2 CF 2 CF 2 O—, CR 4 R 5 CF 2 CF 2 O—, —(CF(CF 3 )CF 2 O)—, —CF 2 CF(CF 3 )O—, wherein X is F or CF 3 , R 4  and R 5  independently have the meaning of H, Cl, or C1-C4 perfluoroalkyl.

[0001] The present invention pertains to a fluorinated resin and the usethereof in antifouling coating compositions for marine applications.

[0002] Man-made structures such as boat hulls, buoys, drillingplatforms, oil production rigs, and pipes which are immersed in waterare prone to fouling by aquatic organisms such as green and brown algae,barnacles, mussels, and the like. Such structures are commonly of metal,but may also comprise other structural materials such as concrete. Thisfouling is a nuisance on boat hulls, because it increases frictionalresistance during movement through the water, the consequence beingreduced speeds and increased fuel costs. It is a nuisance on staticstructures such as the legs of drilling platforms and oil productionrigs, firstly because the resistance of thick layers of fouling to wavesand currents can cause unpredictable and potentially dangerous stressesin the structure, and, secondly, because fouling makes it difficult toinspect the structure for defects such as stress cracking and corrosion.It is a nuisance in pipes such as cooling water intakes and outlets,because the effective cross-sectional area is reduced by fouling, withthe consequence that flow rates are reduced.

[0003] The commercially most successful methods of inhibiting foulinghave involved the use of anti-fouling coatings containing substancestoxic to aquatic life, for example tributyltin chloride or cuprousoxide. Such coatings, however, are being regarded with increasingdisfavour because of the damaging effects such toxins may have ifreleased into the aquatic environment. There is accordingly a need fornon-fouling coatings which do not contain markedly toxic materials.

[0004] It has been known for many years, for example as disclosed in GB1,307,001 and U.S. Pat. No. 3,702,778 that silicone rubber coatingsresist fouling by aquatic organisms. It is believed that such coatingspresent a surface to which the organisms cannot easily adhere, and theycan accordingly be called non-fouling rather than anti-fouling coatings.Silicone rubbers and silicone compounds generally have very low toxicproperties. Silicone rubber coatings have, however, gained littlecommercial acceptance. It is difficult to make them adhere well to thesubstrate surface that is to be protected, and mechanically they arerather weak and liable to damage.

[0005] It is known to use fluorinated polymers for fouling control inanti-fouling or non-fouling coating compositions.

[0006] In JP 04-045170 a fluorinated silicone resin is disclosed whichis obtained by grafting a fluorine-containing acrylate to a siliconeresin having olefinically unsaturated bonds in its terminal groups.

[0007] In JP 61-043668 a coating composition having antifoulingproperties is disclosed which is prepared by compounding an alkyd resinwith a polymer prepared by reacting a fluorine-containing monomer withan acrylate polymer.

[0008] In JP 06-322294 a corrosion protecting antifouling coating isdisclosed comprising a film forming resin and an organopolysiloxanehaving oxyalkylene groups and perfluoroalkyl groups.

[0009] Fluorinated polymers are also known for other uses.

[0010] In JP 06-239876 a fluorinated polymer having excellent wettingproperties is disclosed that is used in an adhesive. In U.S. Pat. No.4,900,474 a perfluoroether group-containing organopolysiloxane isdisclosed that is used as a silicone antifoamer.

[0011] None of the fluorinated polymers that are known in the art havefound wide application in antifouling coating compositions, since theiranti-fouling/foul release properties are not sufficient and/or theirmechanical properties do not make these compositions suited for use onvarious kind of structures that are immersed in water. In particular,the mechanical properties should be such that if applied as a coatingcomposition for a boat hull, said coating composition should havesufficient strength and abrasion resistance to have a service life ofseveral years.

[0012] The object of the present invention is to provide a newantifouling coating composition with very good anti-fouling/foul releaseproperties and sufficient mechanical strength and a process forinhibiting the fouling of a substrate in a marine fouling environmentwherein this new antifouling coating composition is used. This processcomprises forming on a substrate, before exposure of the substrate to amarine fouling environment, a coating comprising a curable fluorinatedresin of the general formula:

W-L-YFC—O—R^(f)—CFY-L-W  (I)

[0013] wherein

[0014] L is an organic linking group;

[0015] Y is F or CF₃;

[0016] W is a group of general formula —Si(R¹)_(α)(OR²)_(3-α), whereinα=0, 1, or 2, preferably α=0, R¹ and R² independently have the meaningof linear or branched C1-C6 alkyl groups, optionally containing one ormore ether groups, or C7-C12 aryl or alkyl groups, and preferably R¹ andR² are C1-C4 alkyl groups;

[0017] R^(f) is a group having an average molecular weight by numberbetween 350 and 8000, preferably between 500 and 3000, and comprisingrepeating units having at least one of the following structures randomlydistributed along the chain:

[0018] —CFXO—, —CF₂CF₂O—, —CF₂CF₂CF₂O—, —CF₂CF₂CF₂CF₂O—, —CR⁴R⁵CF₂CF₂O—,—(CF(CF₃)CF₂O)—, —CF₂CF(CF₃)O—,

[0019] wherein

[0020] X is F or CF₃,

[0021] R⁴ and R⁵ independently have the meaning of H, Cl, or C1-C4perfluoroalkyl.

[0022] L preferably is a divalent linking group, more preferablyselected from one or more of the following:

[0023] a) —(CH₂—(OCH₂CH₂)_(n))_(m)—CO—NR′—(CH₂)_(q),

[0024] wherein

[0025] R′ is H, C₁-C₄ alkyl or a phenyl group;

[0026] m is an integer equal to 0 or 1, preferably 1;

[0027] n is an integer in the range 0-8, preferably 0-5;

[0028] q is an integer in the range 1-8, preferably 1-3;

[0029] b) —CH₂O—CH₂CH₂CH₂—

[0030] c) —CH₂O—CH₂—CH(OH)CH₂—S—(CH₂)_(q)

[0031] L can also be a trivalent group. In this case in formula (I) -L-Wbecomes -L-(W)₂.

[0032] Preference is given to a compound wherein L is A) with m=1,n=0-5, and q=1-3.

[0033] Further preference is given to R^(f) being selected from one ofthe following structures:

[0034] 1) —(CF₂O)_(a′)—(C₂F₄O)_(b′)—, wherein a′/b′ is between 0,2 and2, a′ and b′ being integers giving the above molecular weight;

[0035] 2) —(C₃F₆O)_(r)—(C₂F₄O)_(b)—(CFXO)_(t)—, wherein r/b is between0,5 and 2 and (r+b)/t is between 10 and 30, b, r, and t being integersgiving the above molecular weight;

[0036] 3)—(C₃F₆O)_(r′)—(CFXO)_(t′)—CF₂(R′f)_(y)—CF₂O—(CFXO)_(t′)—(C₃F₆O)_(r′)—,wherein t′ is larger than 0, r′/t′ is between 10 and 30, r′ and t′ beingintegers giving the above molecular weight, y is 0 or 1, and R′f is aC1-C4 fluoroalkyl group;

[0037] 4) —(C₃F6O)_(z)—CF₂—(R′f)_(y)—CF₂O—(C₃F₆O)_(z)—, wherein z is aninteger giving the above molecular weight, y is 0 or 1, and R′f is aC1-C4 fluoroalkyl group;

[0038] 5) —(OCF₂CF₂CR⁴R⁵)_(q)—OCF₂—(R′f)_(y)—CF₂O—(CR⁴R⁵CF₂CF₂O)_(s)—,wherein q and s are integers giving the above molecular weight, R⁴ andR⁵ have the meaning given above, y is 0 or 1, and R′f is a C1-C4fluoroalkyl group.

[0039] In the above structures —(C₃F₆O)— can be —(CF(CF₃)CF₂O)—or—(CF₂CF(CF₃)O)—. The product of formula (I) can be prepared by themethod disclosed in U.S. Pat. No. 4,746,550.

[0040] Good results in foul release and/or mechanical strength werefound for a coating composition comprising the fluorinated resin offormula (I) that is obtainable by reacting a silicon compound, asdefined below, with bifunctional perfluoropolyethers having —OH or —COORend groups, with R═H or C1-C3 of the general formula:

H—(OCH₂CH₂)_(n)—OCH₂—CF₂—O—R^(f)—CF₂—CH₂O—(CH₂CH₂O)_(n)—H  (II)

or

ROOC—CF₂—O—R^(f)—CF₂—COOR  (III)

[0041] wherein R^(f) and n have the meaning as defined before. Thesecompounds are commercially available from Ausimont under the namesFomblin® ZDOL, ZDEAL, ZDOL-TX. However, it is also possible to usebifunctional perfluoroethers having other end groups, e.g., epoxy groups

[0042] Examples of suitable silicon compounds which can be reacted withthe above bifunctional perfluoropolyether precursors are compounds ofthe general formula

R³—Si—(R⁴)₃  (IV)

[0043] wherein R³ is a group capable of coupling the silicon compound tothe fluorinated polyether and the R⁴ groups each independently have themeaning of an ether or ester group, preferably a group including astraight-chain or branched alkyl moiety having from 1 to 4 carbon atoms.

[0044] For example, a silicon compound in which R³ is anisocyanate-functional group can be coupled to a fluorinated polyetherhaving at least two functional groups selected from hydroxyl, amine, orcarboxylic acid-functional groups. A silicon compound in which R³ is anamine-functional group can be coupled to a fluorinated polyether havingat least two functional groups selected from carboxylic acid ester orepoxy-functional groups. A silicon compound in which R³ is athiol-functional group can be coupled to a fluorinated polyether havingat least two epoxy-functional groups.

[0045] Examples of preferred silicon compounds are alkoxyalkylsilylisocyanates, alkoxysilyl alkyl isocyanates, alkoxy silanes, alkoxyalkylsilanes, and alkoxyalkylsilyl mercapto-, amino-, and glycidyl-functionalcompounds, such as

[0046] 3-methyldimethoxy silylpropyl isocyanate,

[0047] 3-trimethoxy silylpropyl isocyanate,

[0048] 3-triethoxy silylpropyl isocyanate,

[0049] 3-mercaptopropyl trimethoxy silane,

[0050] 3-mercaptopropyl methyldimethoxy silane,

[0051] 3-aminopropyl trimethoxy silane,

[0052] 3-aminopropyl triethoxy silane, and

[0053] 3-glycidoxypropyl trimethoxy silane.

[0054] The thus obtained fluorinated resins are also the subject of thepresent invention.

[0055] In general, good results in both anti/non-fouling properties andmechanical strength are found when the fluorinated resin has a T_(g) inthe range from −120 to 20° C. and a surface energy in the range from 10to 25 mN/m. In general, mechanical properties improve when the T_(g) ofthe resin is increased, foul release properties improve when the T_(g)of the material is lowered. So, for each fluorinated resin an optimumbalance has to be found between mechanical properties and foul releaseproperties by tuning the T_(g) of the resin. This tuning can, e.g., bedone by varying the length of the R^(f) segment or the W segment

[0056] A coating composition can be prepared by mixing the fluorinatedresin, a curing catalyst, for example a condensation catalyst,optionally a co-catalyst, optionally a crosslinker for the resin, areactive or non-reactive fluid additive, solvents, fillers, pigmentsand/or thixotropes.

[0057] Examples of catalysts that may be used include the carboxylicacid salts of various metals, such as tin, zinc, iron, lead, barium, andzirconium. The salts preferably are salts of long-chain carboxylicacids, for example dibutyltin dilaurate, dibutyltin dioctoate, ironstearate, tin (II) octoate, and lead octoate. Further examples ofsuitable catalysts include organobismuth and organotitanium compoundsand organo-phosphates such as 2-ethyl-hexyl hydrogen phosphate. Otherpossible catalysts include chelates, for example dibutyltinacetoacetonate. Further, the catalyst may comprise a halogenated organicacid, which has at least one halogen substituent on a carbon atom whichis in α-position relative to the acid group and/or at least one halogensubstituent on a carbon atom which is in β-position relative to the acidgroup, or a derivative which is hydrolysable to form such an acid underthe conditions of the condensation reaction.

[0058] The presence of a cross-linker for the resin is only necessary ifthe resin cannot be cured by condensation. This depends on thefunctional groups that are present in the fluorinated resin. In general,when the fluorinated resin comprises alkoxy groups, the presence of across-linker is not necessary. If the fluorinated resin comprisesalkoxy-silyl groups, in general the presence of a small amount of acondensation catalyst and water is sufficient to achieve full cure ofthe coating after application. For these compositions, normallyatmospheric moisture is sufficient to induce curing and as a rule itwill not be necessary to heat the coating composition after application.

[0059] The crosslinker that is optionally present can be a cross-linkingagent comprising a functional silane and/or one or more oxime groups.Examples of such cross-linking agents are presented in WO99/33927.Mixtures of different cross-linkers can also be used

[0060] Examples of reactive or non-reactive fluid additives that can beused in the coating composition according to the present invention arenon- or monofunctional fluorinated polyethers. These compounds can berepresented by the following structure:

T-O—CFY—O—R^(f)—CFY-(L)_(f)-T₁  (V)

[0061] wherein

[0062] k is an integer 0 or 1,

[0063] T is selected from —CF₃, —C₂F₅, —C₃F₇, CF₂C₁, C₂F₄C₁, C₃F₆Cl,

[0064] T₁=-O-T when k=0, T₁=W when k is 1.

[0065] and wherein R^(f), Y, and L have the meaning as defined before.

[0066] Commercial products are available from Ausimont, e.g. Fomblin®Y25. Other unreactive oils such as silicone oil, especiallymethyl-phenyl silicone oil, petrolatum, polyolefin oil, or apolyaromatic oil can also be used. The proportion of these reactive ornon-reactive fluid additives may be in the range of from 0 to 25% byweight, based on the total weight of the coating composition.

[0067] Examples of solvents that can be used in the coating compositionaccording to the present invention include polar solvents or mixturesthereof, such as methyl isobutyl ketone or butyl acetate. Non-polarsolvents or mixtures thereof, for example xylene, can be used asco-solvents

[0068] Examples of fillers that can be used in the coating compositionaccording to the present invention are barium sulphate, calciumsulphate, calcium carbonate, silicas or silicates (such as talc,feldspar, and china clay), aluminium paste/flakes, bentonite or otherclays. Some fillers may have a thixotropic effect on the coatingcomposition. The proportion of fillers may be in the range of from 0 to25% by weight, based on the total weight of the coating composition.

[0069] Examples of pigments that can be used in the coating compositionaccording to the present invention are black iron oxide and titaniumdioxide. The proportion of pigments may be in the range of from 0 to 10%by weight, based on the total weight of the coating composition.

[0070] The coating composition can be applied by normal techniques, suchas brush, roller or spray (airless and conventional). To achieve properadhesion to the substrate it is preferred to apply the anti/non-foulingcoating composition to a primed substrate. The primer can be anyconventional primer/sealer coating system. Good results were found, inparticular with respect to adhesion, when using a primer that comprisesan acrylic siloxy-functional polymer, a solvent, a thixotropic agent,filler, and, optionally, a moisture scavenger. Such a primer isdisclosed in WO 99/33927.

[0071] It is also possible to apply the coating composition in theprocess according to the present invention on a substrate containing anaged anti-fouling coating layer. Before the coating composition isapplied to such an aged layer, this old layer is cleaned byhigh-pressure water washing to remove any fouling. The primer disclosedin WO 99/33927 can be used as a tie coat between the aged coating layerand the coating composition according to the present invention. Ingeneral, low-surface energy coatings such as coatings comprisingsilicones or fluoropolymers do not provide a sound base for applicationof the coating composition according to the present invention, not evenafter the application of a tie-coat, since the adhesion between the agedcoating layer and the freshly applied coating layer in general isinsufficient.

[0072] After the coating has been cured, it can be immersed immediatelyand gives immediate anti-fouling and fouling release protection.

[0073] As indicated above, the coating composition used in the processaccording to the present invention has very good anti-fouling and foulrelease properties in combination with a high mechanical strength. Thismakes these coating compositions very suitable for use as anti-foulingor non-fouling coatings for marine applications. The coating can be usedfor both dynamic and static structures, such as boat hulls, buoys,drilling platforms, oil production rigs, and pipes which are immersed inwater. The coating can be applied on any substrate that is used forthese structures, such as metal, concrete, wood or fibre-reinforcedresin.

[0074] The coating compositions used in the process according to thepresent invention are preferably applied as high solids formulations.These compositions comprise less than 30% by weight of solvent,preferably less than 20%, still more preferably less than 10%. Theseformulations belong to the class of solventless coatings. Such coatingshave minimal environmental impact in view of their low solvent content.

[0075] The combination of low (ambient) temperature curing of the resinsand high solids content of the coating composition makes the coatingcompositions according to the present invention suitable for applicationin the open field.

[0076] The invention will be elucidated with reference to the followingexamples. These are intended to illustrate the invention, but are not tobe construed as limiting in any manner the scope thereof.

EXAMPLES Example 1

[0077] Preparation of an Adduct of a Perfluoroether

[0078] 200 pbw of a bifunctional perfluoropolyether of formula (II)having n=0 and a number average molecular weight of 1000 were added to aflange-topped reaction vessel with a mechanical stirrer, a temperatureprobe, a water condenser, and a feed inlet. After the addition of 0,02pbw of dibutyltin dilaurate (DBTDL), the reaction vessel was heated to70° C. At this temperature, 88 pbw of3-(trimethoxysilylpropyl)isocyanate (TMSPI) were added dropwise over atwo-hour period. During the addition the temperature was maintained at70° C. using a temperature control unit. After the completion of thefeed, the solution was stirred for another hour to complete thereaction. The progress of the reaction could be monitored by measuringthe decrease of the infrared absorption of TMSPI at ˜2270 cm⁻¹.

[0079] The adduct has a viscosity at 25° C. of 4,1 Poise (0,41 Pa.s) anda T_(g) of −26° C.

Example 2

[0080] Preparation of an Adduct of an Ethoxylated Perfluoroether

[0081] Using the same process as described in Example 1, a bifunctionalperfluoropolyether of formula (II) having n=1,5 and a number averagemolecular weight of 2000 was used as a perfluoroether starting componentin the reaction.

[0082] The formed adduct has a viscosity at 25° C. of 8,1 Poise (0,81Pa.s) and a T_(g) of −97° C.

Example 3

[0083] Using the process of Example 1, a perfluorinated adduct wasobtained by a reaction between a bifunctional diester of formula (III)wherein R═CH₃ having a number average molecular weight of 2000 and anequimolar amount of 3-aminopropyl trimethoxysilane at 70° C. During thereaction methanol was removed by distillation until the ester IR-band atabout 1800 cm⁻¹ had disappeared completely.

Example 4

[0084] A one-pack coating composition was prepared by combining

[0085] 100 g of the adduct of a perfluoroether of Example 1

[0086] 10 g of butyl acetate

[0087] 0,2 g of 3-aminopropyl trimethoxy silane

[0088] 0,1 g of dibutyltin dilaurate

[0089] After application of this coating composition on a woodensubstrate and curing of the composition, a coating was obtained with amodulus at 20° C. of 42,5 Mpa (measured in accordance with ASTM D1708)and a pencil hardness of 3H (measured in accordance with ASTM D3363)

Example 5

[0090] A one-pack coating composition was prepared by combining

[0091] 100 g of the adduct of a perfluoroether of Example 1

[0092] 20 g of butyl acetate

[0093] 0,2 g of 3-aminopropyl trimethoxy silane

[0094] 0,1 g of dibutyltin dilaurate

[0095] 3 g of Fomblin Y-25 (a perfluorinated polyether, ex Ausimont)

Example 6

[0096] A two-pack coating composition was prepared by having

[0097] 100 g of the adduct of a perfluoroether of Example 2

[0098] in one pack and combining

[0099] 10 g of butyl acetate

[0100] 0,2 g of 3-aminopropyl trimethoxy silane

[0101] 0,1 g of dibutyltin dilaurate

[0102] in the other pack.

[0103] After application of this coating composition on a woodensubstrate and curing of the composition, a coating was obtained with amodulus at 20° C. of 3,1 Mpa (measured in accordance with ASTM D1708)and a pencil hardness of 4B (measured in accordance with ASTM D3363)

Example 7

[0104] A one-pack coating composition was prepared by combining

[0105] 100 g of the adduct of a perfluoroether of Example 1

[0106] 10 g of butyl acetate

[0107] 0,2 g of 3-aminopropyl trimethoxy silane

[0108] 0,1 g of dibutyltin dilaurate

[0109] 30 g of talc

[0110] 6 g of black iron oxide

[0111] 25 g of aluminium flake

Example 8

[0112] A one-pack coating composition was prepared by combining

[0113] 100 g of the adduct of a perfluoroether of Example 2

[0114] 20 g of butyl acetate

[0115] 1 g of 2-ethylhexylhydrogen phosphate

[0116] 3 g of Fomblin Y-25 (a perfluorinated polyether, ex Ausimont)

[0117] The coating compositions of Examples 4-8 were applied to woodsubstrates bearing an anti-corrosive undercoat and coating primers asdisclosed in WO 99/33927. The coating formulations were applied by brushand roller to give a layer of average dry film thickness in the rangefrom 25 to 75 μm.

[0118] For static anti-fouling assessment the coated substrates wereimmersed in a marine estuary known for its weed, slime, hard-shelled andsoft-bodied animal fouling. After one season (February-October) theaccumulated fouling was significantly less than that of controlsubstrates not coated with the compositions and maintained under thesame conditions over the same period of time. Any fouling on thesubstrates with the compositions of Examples 4-8 could be removed easilyby light rubbing or low-pressure water jet. Accumulated fouling on thecontrol substrates immersed over the same period could not be removed ina similar way.

[0119] For these coating compositions the following quantitative foulingproperties were found: Ex- am- % micro % soft-bodied % hard-bodied %total Push-off ple fouling animal animal fouling (PSI)* 4 25 1.7 56.783.4 20.55 5 23.8 3.5 41.3 68.6 11.04 6 28.8 2.2 50 81 13.34 7 19.7 2.26.8 28.7 6.24 8 51.4 4.2 22.4 78 9.11

Example 9

[0120] A coating composition was prepared by combining

[0121] 100 g of the adduct of a perfluoroether of Example 3

[0122] 20 g of butyl acetate

[0123] 1 g of 2-ethylhexylhydrogen phosphate

[0124] 3 g of Fomblin Y-04 (a perfluorinated polyether, ex Ausimont)

Example 10

[0125] A coating composition was prepared by combining

[0126] 100 g of the adduct of a perfluoroether of Example 2

[0127] 20 g of butyl acetate

[0128] 15 g of titaniumdioxide

[0129] 1 g of 2-ethylhexylhydrogen phosphate

[0130] 6 g of Fomblin Y-25 (a perfluorinated polyether, ex Ausimont)

[0131] The coating compositions of Examples 9 and 10 were applied towood substrates bearing an anti-corrosive undercoat and coating primersas disclosed in WO 99/33927. The coating formulations were applied bybrush and roller to give a layer of average dry film thickness in therange from 25 to 75 μm.

[0132] For static anti-fouling assessment the coated substrates wereimmersed in a marine estuary known for its weed, slime, hard-shelled andsoft-bodied animal fouling.

1. A process for inhibiting the fouling of a substrate in a marinefouling environment, which comprises forming on the substrate, beforeexposure to the said environment, a coating comprising a curablefluorinated resin of the general formula: W-L-YFC—O—R^(f)—CFY-L-Wwherein L is an organic linking group; Y is F or CF₃; W is a group ofgeneral formula —Si(R¹)_(α)(OR²)_(3-α), wherein α=0, 1, or 2, R¹ and R²independently have the meaning of linear or branched C1-C6 alkyl groups,optionally containing one or more ether groups, or C7-C12 aryl or alkylgroups; R^(f) is a group having an average molecular weight by numberbetween 350 and 8000, comprising repeating units having at least one ofthe following structures randomly distributed along the chain: —CFXO—,—CF₂CF₂O—, —CF₂CF₂CF₂O—, —CF₂CF₂CF₂CF₂O—, —CR⁴R⁵CF₂CF₂O—,—(CF(CF₃)CF₂O)—, —CF₂CF(CF₃)O—, wherein X is F or CF₃, R⁴ and R⁵independently have the meaning of H, Cl, or C1-C4 perfluoroalkyl.
 2. Aprocess according to claim 1, characterised in that the organic linkinggroup L is selected from one or more of the following groups: a)—(CH₂—(OCH₂CH₂)_(n))_(m)—CO—NR′—(CH₂)_(q), b) —CH₂O—CH₂CH₂CH₂— c)—CH₂O—CH₂—CH(OH)CH₂—S—(CH₂)_(q) wherein R′ is H, C₁-C₄ alkyl or a phenylgroup; m is an integer equal to 0 or 1; n is an integer in the range0-8; q is an integer in the range 1-8;
 3. A process according to claim2, characterised in that the organic linking group L has the formula—(CH₂—OCH₂CH₂—CO—NR′—(CH₂)_(q) wherein n is an integer in the range 0-5and q is an integer in the range 1-3.
 4. A process according to any oneof the preceding claims, characterised in that R^(f) is selected fromone or more of the following groups: 1) —(CF₂O)_(α′—(C) ₂F₄O)_(b′)—,wherein a′/b′ is between 0,2 and 2, a′ and b′ being integers giving amolecular weight in the range from 350 to 8000; 2)—(C₃F₆O)_(r)—(C₂F₄O)_(b)—(CFXO)_(t)—, wherein r/b is between 0,5 and 2and (r+b)/t is between 10 and 30, b, r, and t being integers giving amolecular weight in the range from 350 to 8000; 3)—(C₃F₆O)_(r)′—(CFXO)_(t′)—CF₂(R′f)_(y)—CF₂O—(CFXO)_(t′)—(C₃F₆O)_(r′)—,wherein t′ is larger than 0, r′/t′ is between 10 and 30, r′ and t′ beingintegers giving a molecular weight in the range from 350 to 8000, y is 0or 1, and R′f is a C1-C4 fluoroalkyl group.; 4)—(C₃F₆O)z—CF₂—(R′f)_(y)—CF₂O—(C₃F₆O)_(z)—, wherein z is an integergiving a molecular weight in the range from 350 to 8000, y is 0 or 1,and R′f is a C1-C4 fluoroalkyl group; 5)—(OCF₂CF₂CR⁴R⁵)_(q)—OCF₂—(R′f)_(y)—CF₂O—(CR⁴R⁵CF₂CF₂O)_(s)—, wherein qand s are integers giving a molecular weight in the range from 350 to8000, R⁴ and R⁵ have the meaning given above, y is 0 or 1, and R′f is aC1-C4 fluoroalkyl group; whereby in the above structures —(C₃F₆O)— canbe —(CF(CF₃)CF₂O)— or —(CF₂CF(CF₃)O)—.
 5. A process according to any oneof the preceding claims, characterised in that the fluorinated resin hasa T_(g) in the range from −120 to 20° C. and a surface energy in therange from 10 to 25 mN/m.
 6. A process according to any one of thepreceding claims, characterised in that it further comprises anon-functional or mono-functional resin of the general formula:T-O—CFY—O—R^(f)—CFY-(L)_(k)-T₁ wherein k is an integer 0 or 1; T isselected from —CF₃, —C₂F₅, —C₃F₇, CF₂C₁, C₂F₄C₁, C₃F₆Cl; T₁=-O-T whenk=0, T₁=W when k is 1 L is an organic linking group; Y is F or CF₃; andR^(f) is a group having an average molecular weight by number between350 and 8000, comprising repeating units having at least one of thefollowing structures randomly distributed along the chain: —CFXO—,—CF₂CF₂O—, —CF₂CF₂CF₂O—, —CF₂CF₂CF₂CF₂O—, —CR⁴R⁵CF₂CF₂O—,—(CF(CF₃)CF₂O)—, —CF₂CF(CF₃)O—, wherein X is F or CF₃; R⁴ and R⁵independently have the meaning of H, Cl, or C1-C4 perfluoroalkyl.
 7. Useof a curable fluorinated resin of the general formula:W-L-YFC—O—R^(f)—CFY-L-W wherein L is an organic linking group; Y is Fror CF₃; W is a group of general formula —Si(R¹)_(α)(OR²)_(3-α), whereinα=0, 1, or 2,R¹ and R² independently have the meaning of linear orbranched C1-C6 alkyl groups, optionally containing one or more ethergroups, or C7-C12 aryl or alkyl groups; R^(f) is a group having anaverage molecular weight by number between 350 and 8000, comprisingrepeating units having at least one of the following structures randomlydistributed along the chain: —CFXO—, —CF₂CF₂O—, —CF₂CF₂CF₂O—,—CF₂CF₂CF₂CF₂O—, CR⁴R⁵CF₂CF₂O—, —(CF(CF₃)CF₂O)—, —CF₂CF(CF₃)O—, whereinX is F or CF₃, R⁴ and R⁵ independently have the meaning of H, Cl, orC1-C4 perfluoroalkyl, in antifouling or non-fouling coating compositionsfor marine use.
 8. Use according to claim 7, characterised in that thefluorinated resin has a T_(g) in the range from −120 to 20° C. and asurface energy in the range from 10 to 25 mN/m.